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BUG: KCSAN: data-race in ext4_ext_insert_extent / ext4_mark_iloc_dirty

read-write to 0xffff88813a80c142 of 2 bytes by task 26 on cpu 1:
 le16_add_cpu include/linux/byteorder/generic.h:146 [inline]
 ext4_ext_insert_extent+0x1981/0x2b50 fs/ext4/extents.c:2113
 ext4_ext_map_blocks+0x16a3/0x1fc0 fs/ext4/extents.c:4259
 ext4_map_blocks+0x700/0xfc0 fs/ext4/inode.c:637
 mpage_map_one_extent+0x10d/0x390 fs/ext4/inode.c:2396
 mpage_map_and_submit_extent fs/ext4/inode.c:2449 [inline]
 ext4_writepages+0xa51/0x1e50 fs/ext4/inode.c:2801
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __writeback_single_inode+0x84/0x560 fs/fs-writeback.c:1461
 writeback_sb_inodes+0x6a0/0x1020 fs/fs-writeback.c:1721
 wb_writeback+0x27d/0x660 fs/fs-writeback.c:1894
 wb_do_writeback+0x101/0x5d0 fs/fs-writeback.c:2039
 wb_workfn+0xb8/0x410 fs/fs-writeback.c:2080
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x635/0xb90 kernel/workqueue.c:2421
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff88813a80c140 of 4 bytes by task 10056 on cpu 0:
 ext4_do_update_inode fs/ext4/inode.c:5114 [inline]
 ext4_mark_iloc_dirty+0xcc3/0x1650 fs/ext4/inode.c:5721
 __ext4_mark_inode_dirty+0x4cd/0x5d0 fs/ext4/inode.c:5915
 ext4_dirty_inode+0xa6/0xc0 fs/ext4/inode.c:5951
 __mark_inode_dirty+0x72/0x6b0 fs/fs-writeback.c:2260
 mark_inode_dirty include/linux/fs.h:2181 [inline]
 generic_write_end+0x15e/0x250 fs/buffer.c:2202
 ext4_da_write_end+0x59b/0x760 fs/ext4/inode.c:3111
 generic_perform_write+0x23e/0x3a0 mm/filemap.c:3419
 ext4_buffered_write_iter+0x2e5/0x3d0 fs/ext4/file.c:270
 ext4_file_write_iter+0x45e/0x1090 fs/ext4/file.c:503
 call_write_iter include/linux/fs.h:1901 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x6d4/0x7c0 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10056 Comm: syz-executor.5 Not tainted 5.11.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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